Halogen ion-modified silver nanoparticles for ultrasensitive surface-enhanced Raman spectroscopy detection of polycyclic aromatic hydrocarbons.

Rapid ultrasensitive detection of trace polycyclic aromatic hydrocarbons (PAHs) is essential and significant for pollution control due to their hazard, persistence, and the wide distribution in the environment. Therefore, rapid detection of PAHs is critical for controlling pollution and protecting the ecology. Considering the advantages of surface-enhanced Raman spectroscopy (SERS), a simple and reliable SERS method was proposed in this work for detecting PAHs in water. Three chemicals, namely NaCl, KBr, and KI, were chosen to modify Ag nanoparticles (NPs) for phenanthrene (Phe) detection, and Ag NPs modified with KBr (Ag-Br NPs) showed the best SERS response. The mixing sequence and the concentration of KBr were optimized. The addition order of mixing KBr and Ag NPs before Phe solution was the best sequence, and the optimal concentration of KBr was 20 mM. Under optimal conditions, the limits of quantification for Phe, pyrene (Pyr), and anthracene (Ant) were 10-6  M, 10-7  M, and 10-7  M, respectively. Mixed PAHs (Phe, Pyr, and Ant) in spiked water samples were identified and quantified successfully. The proposed method has good application prospects in environmental pollution monitoring.

Microwave disinfection strengthened by a biochar-based microwave absorbing material for sewage resource utilization.

Proper disinfection treatment is the basic guarantee for safe utilisation of sewage. However, the commonly used disinfection methods are not suitable for nutrients containing reclaimed water. In this work, the microwave disinfection method assisted by a microwave-absorbing material in recycled water samples was investigated. Magnetic corn stalk biochar (MCSB), the microwave absorbing material, was prepared by high temperature carbonisation of corn stalk particles impregnated with ferrous sulfate. Escherichia coli and fecal coliforms were selected as target microorganisms to investigate the disinfection efficiency of MCSB assisted microwave radiation (MW/MCSB). The addition of microwave absorbing materials significantly improves the disinfection effect of water samples. Compared with the microwave radiation (MW) without MCSB, the bactericidal rate by using 107 CFU/L E. coli suspension increased from 63.5% to 100% at 480 W for 30 s after adding 4 g/L MCSB. Besides, the effects of MCSB dosage, microwave power, microwave radiation time, and initial bacterial concentration on disinfection efficiency were explored. Moreover, the bactericidal efficiency for actual sewage samples was also demonstrated by treating the effluent from septic tank sewage. The residual fecal coliforms in treated water samples met China's farmland irrigation water standard (GB 5084-2021). The result indicates that the proposed method of microwave disinfection strengthened by MCSB has a promising application prospect for reclaimed water disinfection.